waecmaths question:
If x + y = 12 and 3x – y =20, find the value of 2x – y
Option A:
8
Option B:
10
Option C:
12
Option D:
15
waecmaths solution:
$\begin{align} & x+y=12-----(i) \\ & 3x-y=20----(ii) \\ & \text{Add the two equations together} \\ & 4x=32 \\ & x=8 \\ & y=12-8=4 \\ & \therefore 2x-y=2(8)-4 \\ & 2x-y=16-4=12 \\\end{align}$
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